Outbreaks of head lice, pediculus humanus Capitis, are near epidemic. In the United States it is estimated that ten to twelve million cases occur annually. This public health problem is considered by the uninformed to result from poor personal cleanliness. Thus the presence of head lice carries a social stigma. In actuality, poor personal cleanliness is not a major factor. Lice afflict individuals regardless of socio-economic status and in spite of adequate cleanliness. Infestation is endemic in populations of relatively high density where there is close physical contact and contact with articles used by others. Direct contact, as well as contact with combs, towels, bed linens, and/or clothing, are among things that can transfer the bugs. Unfortunately such contact is frequent in schools, particularly those with the very young; in summer camps; in military quarters and the like. These are characterized by high population density.
The approaches to treatment are insecticidal combined with manual removal, ovicidal with manual removal and simple manual removal.
Many insecticidal and ovicidal products have been used in the past. Some, once popular, have been removed from use because of extremely serious side effects especially when used on the young. Lindane is one example. Malathion is used but is extremely dangerous. There are natural products, folk remedies, that are of doubtful efficacy, which include mayonaise, vaseline, tea tree oil, and olive oil. These too have associated hazards often acting as growth sites for bacteria. There are natural products, remedies with insecticidal properties, that, being strong enough to kill lice, are seriously harmful to the skin of humans and can cause systemic disruptions. Many treatments are based on Pyrethrin and/or Permethrin. Again, the strengths needed can be harmful to the very young who are the most typical victims often through allergies. The FDA provides voluminous Adverse Effects reports listing serious side effects, including death, associated with use of pedulicides.
In addition, there is a large body of evidence indicating that the lice are becoming resistant to these chemicals as reported in PEDI Vol. 153 No. 9 pp 969–973 by Pollack et al. comparing treatment with permethrin of children suffering from pediculiasis in Massachusetts with similar children in Borneo. Most of the US children had previously been treated for lice. It was concluded that head lice in the United States are less susceptible to pyrethroids than those in Borneo where there is no history of prior exposure to the treatment. Similarly, a study in Israel ,Mumcuoglu et al., Medical and Veterinary Entomology (1995) 9. 427–432 concluded that lice were rapidly becoming resistant to permethrin; and in the Czech Republic, Rupes et al., Centr. Eur J. publ Hlth 3 no. 1. p. 330–32, found resistance to pyrethroids after exclusive use of lotions with cross-resistance to d-phenothrin and bioalethrin. Nevertheless, over-the-counter medications containing pediculicides and/or ovicides continue to be available for treatment of head lice.
In U.S. Pat. No. 4,518,593. Jouvin et al. teach an insecticide composition in the form of a shampoo that comprises 74–95% by volume of one of ammonium, triethanolamine, and sodium lauryl sulphate as a wetting agent, 2–12% by volume of acetic acid and 0.5–3% by volume of at least one of the group of natural or synthetic extracts or essences of clove, lavender, peppermint, organum, rosemary, lime, juniper, lemon, citronella, thyme, Datura Stramonium, pine, pyrethrum, pyrethrin and Ceylon cinnamon leaves, the pH of the composition being less than 4.5. The teaching is that the composition is effective in killing head lice. One of skill might well feel that the product is effective with such strong pediculocides as pyrethrin and that it should not be used on a frequent basis. This is especially so if the upper range of the acid is present. More important, insecticides, synthetic or natural, should not be in daily use for fear of harming the patient by absorption through the skin or at least harming the scalp and hair of the patient. As there is resistance to treatment on the part of typical users, the chance of overdose increases as parents, for example, use larger and more frequent doses than directed in order to obtain positive results.
Consider the pure manual approach. The National Pediculosis Association® (NPA), which can be contacted at http://www.headlice.org/, strongly urges manual removal to avoid the hazards associated with the strong chemicals, both natural and synthetic, required to kill lice. Their methodology involves the use of a fine-tooth comb (such as the LiceMeister® available from NPA) after careful de-tangling of the strands, augmented by tweezers, fingernails and p rhaps with double sided tape on a finger. Daily screening is recommended and frequent repetition of the procedure maybe required. One reason for this is because nits, the eggs, are extremely hard to remove and, if left, hatch new larvae. Another reason is that re-infestation often occurs because the victim continues to inhabit the environment where the infestation started. Moreover, manual removal is time-consuming and difficult. The lice and nits are firmly attached and hard to see. In addition, small children often object to combing with a fine tooth comb because the pulling action can be painful. This makes it unlikely that a consistent treatment course will be completed and can result in overlooked, live lice or, much more likely, nits that will insure re-infestation.
Therefor it is the object of this invention to provide a shampoo in combination with a hair conditioner that is gentle enough for daily use, beneficial to the hair, and does not contain harmful insecticides. It is an object to avoid toxicity and yet to be active in aiding manual removal of lice and nits by dislodging them. It is a further object to make fine combing painless for the victim so that a daily regimen can be followed with ease. Further, because many desirable ingredients mix poorly, it is an object of this invention to present a formula that meets the prime objectives and is stable. It is still a further object to provide a formulation that actively repels lice.